1. Field of the Invention
This invention relates to a process for preparing permeable adhesive tapes. More particularly, it relates to an industrially advantageous process for preparing permeable adhesive tapes which comprises making holes with the aid of water, or water and a water absorptive high-molecular weight compound.
2. Description of the Prior Art
The present invention is specifically directed to adhesive tapes used for protecting wounds or others. The adhesive tapes referred to herein are meant to include adhesive bandages, sticking plasters, bandages, surgical cloths and so forth by way of example. Such adhesive tapes cause maceration when adhered and maintained on skin for a long time. For avoiding this problem, it is desirous that tapes have permeability. In order to solve this problem, the prior arts provides holes in tapes by using the following many methods:
(i) mechanically, for instance, by punching the product: PA0 (ii) chemically, for instance, by incorporating a substance which can be leached out by a solvent into the product; PA0 (iii) physically, for instance, by causing the product to foam by expelling a solvent during drying, thus making the material microporous. PA0 (iv) by physical interaction between the backing material and the adhesive, for example, by allowing the adhesive to dry in contact with a fabric backing material which causes the adhesive to become porous.
The method of this invention relates to rendering the material microporous, as mentioned in (iii). Examples of the prior arts classified in (iii) are "Micropore" (trademark of 3M in USA), tapes disclosed in Japanese Unexamined Patent Publication No. 57(1982)-182375 and the like. For instance, the above No. 57(1982)-182375 discloses that an adhesive layer is formed by using a dispersion of an adhesive agent in an organic solvent and is given for permeability therein.